JP4506251B2 - Separation membrane and method for producing separation membrane - Google Patents
Separation membrane and method for producing separation membrane Download PDFInfo
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- 239000012528 membrane Substances 0.000 title claims description 164
- 238000000926 separation method Methods 0.000 title claims description 110
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 162
- 229910021536 Zeolite Inorganic materials 0.000 claims description 161
- 239000010457 zeolite Substances 0.000 claims description 161
- 239000013078 crystal Substances 0.000 claims description 115
- 239000011148 porous material Substances 0.000 claims description 33
- 239000002002 slurry Substances 0.000 claims description 29
- 238000003786 synthesis reaction Methods 0.000 claims description 12
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 238000000576 coating method Methods 0.000 claims description 2
- 238000003618 dip coating Methods 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 27
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 14
- 239000000377 silicon dioxide Substances 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 10
- 239000002245 particle Substances 0.000 description 10
- 239000010419 fine particle Substances 0.000 description 9
- 239000012466 permeate Substances 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 239000000919 ceramic Substances 0.000 description 6
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 6
- 238000005373 pervaporation Methods 0.000 description 6
- 238000001878 scanning electron micrograph Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000004626 scanning electron microscopy Methods 0.000 description 4
- 235000012239 silicon dioxide Nutrition 0.000 description 4
- 238000005211 surface analysis Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 229910052681 coesite Inorganic materials 0.000 description 3
- 229910052906 cristobalite Inorganic materials 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- 229910052682 stishovite Inorganic materials 0.000 description 3
- 229910052905 tridymite Inorganic materials 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 229910052910 alkali metal silicate Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- -1 aluminum aluminate Chemical class 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000002808 molecular sieve Substances 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 235000019353 potassium silicate Nutrition 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 description 2
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 239000004111 Potassium silicate Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- SMZOGRDCAXLAAR-UHFFFAOYSA-N aluminium isopropoxide Chemical compound [Al+3].CC(C)[O-].CC(C)[O-].CC(C)[O-] SMZOGRDCAXLAAR-UHFFFAOYSA-N 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012510 hollow fiber Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000013081 microcrystal Substances 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 description 1
- 229910052913 potassium silicate Inorganic materials 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 235000019794 sodium silicate Nutrition 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical compound [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 description 1
- BGQMOFGZRJUORO-UHFFFAOYSA-M tetrapropylammonium bromide Chemical compound [Br-].CCC[N+](CCC)(CCC)CCC BGQMOFGZRJUORO-UHFFFAOYSA-M 0.000 description 1
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Description
本発明は、分離膜構造に関し、詳しくは、浸透成分の透過抵抗を低減して成分透過特性を高めた分離膜構造に関するものである。 The present invention relates to a separation membrane structure, and more particularly to a separation membrane structure in which the permeation resistance of a permeation component is reduced to improve the component permeation characteristics.
ゼオライトは分子程度の大きさの細孔を有する結晶性アルミノケイ酸塩であり、ゼオライトからなる膜は分子のサイズや形状の違いにより選択的に分子を通過させる性質を有するので、分子ふるいとして広く利用されている。なかでも水と有機溶剤等の分離膜としての用途が注目されている。しかしながら、分離膜として機能するゼオライト膜自体は十分な機械的強度を有さないので、セラミックス等からなる多孔質支持体に支持された状態で使用するのが普通である。 Zeolite is a crystalline aluminosilicate with pores about the size of a molecule, and a membrane made of zeolite has the property of selectively passing molecules depending on the size and shape of the molecule, so it is widely used as a molecular sieve. Has been. In particular, the use as a separation membrane for water and organic solvents has attracted attention. However, since the zeolite membrane itself functioning as a separation membrane does not have sufficient mechanical strength, it is usually used in a state of being supported by a porous support made of ceramics or the like.
多孔質支持体に支持されたゼオライト膜は、シリカ源とアルミナ源を主原料とする原料中に多孔質支持体を浸漬させた状態で、水熱反応により製造されている。シリカ源とアルミナ源を含有するスラリー状の原料中に多孔質支持体を浸漬させると、スラリー中の微細なゼオライト種結晶を核としてゼオライト膜が形成される。このため、スラリー中にはゼオライト原料が過飽和となっている必要がある。 The zeolite membrane supported by the porous support is produced by a hydrothermal reaction in a state where the porous support is immersed in a raw material mainly composed of a silica source and an alumina source. When the porous support is immersed in a slurry-like raw material containing a silica source and an alumina source, a zeolite membrane is formed with fine zeolite seed crystals in the slurry as nuclei. For this reason, the zeolite raw material needs to be supersaturated in the slurry.
しかしながら、過飽和のスラリー中に多孔質支持体を浸漬させると、微細なゼオライト種結晶が多孔質支持体の表面に付着してゼオライト膜が成長するのみならず、スラリー中で大きく成長したゼオライト結晶が多孔質支持体の表面に付着してゼオライト膜が成長する。このようにして形成されたゼオライト膜は均一な孔径及び膜厚を有さず、ピンホールが生じやすいという問題がある。このため水熱反応により多孔質支持体上でゼオライト膜を合成する際には、予めセラミックス等の多孔質支持体に種結晶を担持させ、スラリー中のゼオライト原料の濃度を低く設定するのが好ましい。 However, when the porous support is immersed in a supersaturated slurry, not only does the fine zeolite seed crystals adhere to the surface of the porous support and the zeolite membrane grows, but also the zeolite crystals that grow large in the slurry A zeolite membrane grows on the surface of the porous support. The zeolite membrane formed in this way has a problem that it does not have a uniform pore size and film thickness and pinholes are likely to occur. For this reason, when a zeolite membrane is synthesized on a porous support by a hydrothermal reaction, it is preferable to previously support a seed crystal on a porous support such as ceramics and set the concentration of the zeolite raw material in the slurry low. .
多孔質支持体にゼオライトの種結晶を担持させた状態で水熱反応によりゼオライト膜を製造する方法は数多く知られている（例えば特許文献１参照）。上記先行文献には、多孔体の細孔内に予めゼオライト種結晶を担持させ、多孔体をゼオライトスラリー中に浸漬し、水熱合成により前記種結晶を成長させて細孔内にゼオライト膜を生成させる方法が開示されている。
しかしながら、これまでに報告されている方法で作製されたゼオライト膜において、２以上の成分の分離を行なった場合に、高い分離選択性を得ることはできる一方で、透過特性を向上させる方策ならび分離膜の構造を定義するものはこれまでにはなかった。 However, when two or more components are separated in a zeolite membrane prepared by the methods reported so far, high separation selectivity can be obtained, while measures for improving permeation characteristics and separation are achieved. There has never been a definition of the structure of the membrane.
本発明はこのような問題を解決するためになされたもので、高い分離選択性を維持し、かつ、より高い透過特性を実現することができる分離膜を提供するものである。 The present invention has been made to solve such a problem, and provides a separation membrane that can maintain high separation selectivity and realize higher permeation characteristics.
本発明の発明者は、鋭意研究の結果、本発明のような分離膜において、多孔質支持体の細孔内に形成されたゼオライト結晶は、浸透し透過していく成分の透過抵抗となり、分離膜の透過係数の低下を招くこと確認した。そして、支持体内に形成されるゼオライト結晶の総量を減少させることによって、工業的な使用に耐えうる分離膜の特性が得られる分離膜を実現し、本発明に至った。 As a result of earnest research, the inventor of the present invention has found that in a separation membrane such as the present invention, the zeolite crystals formed in the pores of the porous support have permeation resistance of components that permeate and permeate. It was confirmed that the permeability coefficient of the membrane was reduced. Then, by reducing the total amount of zeolite crystals formed in the support, a separation membrane capable of obtaining the characteristics of a separation membrane that can withstand industrial use was realized, and the present invention was achieved.
本発明において、分離膜は、所定の平均細孔径を有する多孔質支持体と、前記多孔質支持体の表面に緻密に形成されたゼオライト膜とからなる分離膜であって、前記ゼオライト膜の表面から１０μｍの深さまでに形成されたゼオライト結晶の総量Ｍ１と、前記ゼオライト膜の表面から１０μｍの深さから前記ゼオライト膜の表面から２０μｍの深さまでに形成されたゼオライト結晶の総量Ｍ２との関係がＭ２／Ｍ１＜０．４であることを特徴とする。 In the present invention, the separation membrane is a separation membrane comprising a porous support having a predetermined average pore diameter and a zeolite membrane densely formed on the surface of the porous support, the surface of the zeolite membrane Between the total amount M1 of zeolite crystals formed to a depth of 10 μm to 10 μm and the total amount M2 of zeolite crystals formed from a depth of 10 μm to the depth of 20 μm from the surface of the zeolite membrane. M2 / M1 <0.4.
本発明のような分離膜において、緻密に形成されたゼオライト膜によって高い分離性能が得られ、多孔質支持体の細孔内に形成されたゼオライト結晶を少量とすることで、上述した透過抵抗を抑制して、分離膜の高い透過特性を得ることができる。
さらに、請求項１において定義したＭ１とＭ２との関係をＭ２／Ｍ１＜０．１２とすることで、分離膜の透過特性をより高いものとすることができる。In the separation membrane as in the present invention, high separation performance is obtained by the densely formed zeolite membrane, and the above-mentioned permeation resistance can be achieved by reducing the amount of zeolite crystals formed in the pores of the porous support. It is possible to obtain a high permeation characteristic of the separation membrane.
Furthermore, by setting the relationship between M1 and M2 defined in claim 1 to M2 / M1 <0.12, the permeation characteristics of the separation membrane can be made higher.
また、本発明の分離膜において、前記ゼオライト膜の表面から４μｍの深さまでに形成されたゼオライト結晶の総量Ｍ３と、前記ゼオライト膜の表面から１２μｍの深さから前記ゼオライト膜の表面から１６μｍの深さまでに形成されたゼオライト結晶の総量Ｍ４との関係がＭ４／Ｍ３＜０．３０であり、より好ましくはＭ４／Ｍ３＜０．０６であることを特徴とする。
この関係は、ゼオライト結晶の密度が高い部分を比較対照としているため、多孔質支持体の細孔内に形成されたゼオライト結晶の量をより顕著に示したものとなっている。この関係式が低い値を示すほどに、高い透過性能を得ることが可能となる。In the separation membrane of the present invention, the total amount M3 of zeolite crystals formed to a depth of 4 μm from the surface of the zeolite membrane, the depth of 12 μm from the surface of the zeolite membrane, and the depth of 16 μm from the surface of the zeolite membrane. The relationship with the total amount M4 of the zeolite crystals formed so far is M4 / M3 <0.30, more preferably M4 / M3 <0.06.
Since this relationship uses a portion where the density of the zeolite crystals is high as a comparative reference, the amount of the zeolite crystals formed in the pores of the porous support is more markedly shown. As this relational expression shows a lower value, higher transmission performance can be obtained.
また、本発明の分離膜の製造方法は、所定の平均細孔径を有する多孔質支持体にゼオライトの種結晶を担持させる種結晶担持工程と、種結晶が担持された前記多孔質支持体を所定の組成で予め用意されたゼオライト合成用反応液内に浸漬させ、水熱反応により多孔質支持体の表面および細孔内にゼオライト結晶を形成する結晶形成工程とを含み、前記多孔質支持体の表面の平均細孔径をＲ、前記種結晶の平均径をＳとしたときに、Ｒ−Ｓ≦１．１μｍであることを特徴とする。この製法によって、上記特徴を有する分離膜が作製可能である。
また、より高い透過特性を有する分離膜を作製するためには、前記多孔質支持体の表面の平均細孔径をＲ、前記種結晶の平均径をＳとしたときに、０．１μｍ≦Ｒ−Ｓ≦０．８μｍとすることが好ましい。平均細孔径が大きすぎると、また、前記種結晶の平均径が０．３μｍ〜０．８μｍとすることが好ましい。また、前記多孔質支持体の表面の平均細孔径が０．４〜１．５μｍであることが望ましい。種結晶の平均径が０．８μｍよりも大きくなると種結晶の担持時に使用するスラリー内において、種結晶が沈殿し、均質に種結晶を担持することが出来ない。また、種結晶が０．３μｍよりも小さいと、種結晶の粒径制御が困難である。また、平均細孔径が１．５μｍよりも大きくなると、多孔質支持体内に多量のゼオライト結晶が形成され、これにより、透過成分の透過抵抗が増大して、透過係数が低下する。これらの理由から、好ましい種結晶の平均径と、好ましい支持体の表面の平均細孔径が与えられる。
なお、この製法の作用効果は、Ｙ型ゼオライト膜では得られない。In addition, the method for producing a separation membrane of the present invention comprises a seed crystal supporting step of supporting a zeolite seed crystal on a porous support having a predetermined average pore diameter, and the porous support supporting the seed crystal is predetermined. A step of immersing in a zeolite synthesis reaction solution prepared in advance, and forming a zeolite crystal on the surface and pores of the porous support by a hydrothermal reaction. R−S ≦ 1.1 μm, where R is the average pore diameter on the surface and S is the average diameter of the seed crystal. By this production method, a separation membrane having the above characteristics can be produced.
In order to produce a separation membrane having higher permeation characteristics, when the average pore diameter on the surface of the porous support is R and the average diameter of the seed crystal is S, 0.1 μm ≦ R− It is preferable that S ≦ 0.8 μm. When the average pore diameter is too large, it is preferable that the average diameter of the seed crystal is 0.3 μm to 0.8 μm. Moreover, it is desirable that the average pore diameter of the surface of the porous support is 0.4 to 1.5 μm. When the average diameter of the seed crystal is larger than 0.8 μm, the seed crystal is precipitated in the slurry used for supporting the seed crystal, and the seed crystal cannot be supported uniformly. If the seed crystal is smaller than 0.3 μm, it is difficult to control the grain size of the seed crystal. On the other hand, when the average pore diameter is larger than 1.5 μm, a large amount of zeolite crystals are formed in the porous support, thereby increasing the permeation resistance of the permeation component and decreasing the permeation coefficient. For these reasons, a preferable average diameter of the seed crystal and a preferable average pore diameter of the surface of the support are given.
In addition, the effect of this manufacturing method cannot be obtained with a Y-type zeolite membrane.
以上説明したように本発明によれば、高い分離選択性を維持し、かつ、より高い透過特性を実現することができる分離膜を提供することができる。 As described above, according to the present invention, it is possible to provide a separation membrane capable of maintaining high separation selectivity and realizing higher permeation characteristics.
以下、本発明の実施の形態について、図面を参照して説明する。
［１］種結晶の多孔質支持体への付着
ゼオライトの合成反応に先立って、多孔質支持体にゼオライトの種結晶を付着させる。得られる種結晶を含む層が厚すぎるとゼオライトの合成反応が主として種結晶を含む層の表面で起こるため、種結晶を含む層の下側では十分に結晶化したゼオライト膜が得られず、ゼオライト膜が剥離しやすくなる。鋭意研究の結果、種結晶の粒子径を調整する必要があり、さらに種結晶を含む層を均一化するには種結晶を含むスラリー中のゼオライト濃度及び多孔質支持体の平均細孔径を調整するのが好ましいことが分かった。以下これらの条件を詳細に説明する。Embodiments of the present invention will be described below with reference to the drawings.
[1] Attachment of seed crystal to porous support Prior to the synthesis reaction of zeolite, a seed crystal of zeolite is attached to the porous support. If the resulting seed crystal-containing layer is too thick, the zeolite synthesis reaction occurs mainly on the surface of the seed crystal-containing layer, so that a sufficiently crystallized zeolite membrane cannot be obtained below the seed crystal-containing layer. The film is easily peeled off. As a result of earnest research, it is necessary to adjust the particle diameter of the seed crystal, and in order to make the layer containing the seed crystal uniform, the zeolite concentration in the slurry containing the seed crystal and the average pore diameter of the porous support are adjusted. It has been found preferable. Hereinafter, these conditions will be described in detail.
（１）種結晶
種結晶は、ゼオライトの微結晶を使用すればよい。種結晶の粒径の頻度分布におけるモードは１ｎｍ〜１μｍであるのが好ましい。また種結晶の９９体積％は粒径５μｍ以下であり、粒径１μｍ以下であるのが好ましい。
ゼオライトの微細粒子を水に入れ、撹拌してスラリーにする。スラリー中に含まれる種結晶の濃度は０．１〜２０質量％であるのが好ましく、０．１〜１０質量％であるのがより好ましい。濃度が０．１質量％未満であると、多孔質支持体に種結晶が均一に付着せず、種結晶のない領域でのゼオライト膜にピンホール等の欠陥が生じるので好ましくない。また濃度を２０質量％超とすると、種結晶を含む層が厚くなりすぎ、外側部分しか結晶化せず、内側の種結晶は十分に結晶化せずに保持されるので、ゼオライト膜の剥離や欠陥が発生し易くなる。(1) Seed crystal As the seed crystal, zeolite microcrystals may be used. The mode in the frequency distribution of the grain size of the seed crystal is preferably 1 nm to 1 μm. Further, 99% by volume of the seed crystal has a particle size of 5 μm or less, and preferably a particle size of 1 μm or less.
Zeolite fine particles are put into water and stirred into a slurry. The concentration of the seed crystal contained in the slurry is preferably 0.1 to 20% by mass, and more preferably 0.1 to 10% by mass. If the concentration is less than 0.1% by mass, the seed crystals are not uniformly adhered to the porous support, and defects such as pinholes occur in the zeolite membrane in the region without the seed crystals. If the concentration exceeds 20% by mass, the layer containing the seed crystal becomes too thick, and only the outer part is crystallized, and the inner seed crystal is retained without being sufficiently crystallized. Defects are likely to occur.
（２）多孔質支持体
多孔質支持体としては、セラミックス、有機高分子又は金属からなるのが好ましく、セラミックスからなるのがより好ましい。セラミックスとしては、ムライト、アルミナ、シリカ、チタニア、ジルコニア等が好ましく、金属としてはステンレススチール、焼結されたニッケル又は焼結されたニッケルと鉄の混合物等が好ましい。(2) Porous support The porous support is preferably made of ceramics, organic polymer or metal, more preferably ceramics. As the ceramic, mullite, alumina, silica, titania, zirconia and the like are preferable, and as the metal, stainless steel, sintered nickel, a mixture of sintered nickel and iron, and the like are preferable.
多孔質支持体上にゼオライト膜を形成したものを分子ふるい等として利用する場合、（ａ）ゼオライト膜を強固に担持することができ、（ｂ）圧損ができるだけ小さく、かつ（ｃ）多孔質支持体が十分な自己支持性（機械的強度）を有するという条件を満たすように、多孔質支持体の細孔径を設定するのが好ましい。具体的には、多孔質支持体の平均細孔径は０．４〜１．２μｍであるのが好ましい。また気孔率は５〜５０％であるのが好ましく、３０〜５０％であるのがより好ましい。
多孔質支持体の形状は特に限定されず、管状、平板状、ハニカム状、中空糸状、ペレット状等、種々の形状のものを使用できる。例えば管状の場合、多孔質支持体の大きさは特に限定されないが、実用的には長さ２〜２００ｃｍ程度、内径０．５〜２ｃｍ、厚さ０．５〜４ｍｍ程度である。In the case where a zeolite membrane formed on a porous support is used as a molecular sieve or the like, (a) the zeolite membrane can be firmly supported, (b) the pressure loss is as small as possible, and (c) the porous support It is preferable to set the pore diameter of the porous support so as to satisfy the condition that the body has sufficient self-supporting property (mechanical strength). Specifically, the average pore diameter of the porous support is preferably 0.4 to 1.2 μm. The porosity is preferably 5 to 50%, more preferably 30 to 50%.
The shape of the porous support is not particularly limited, and various shapes such as a tubular shape, a flat plate shape, a honeycomb shape, a hollow fiber shape, and a pellet shape can be used. For example, in the case of a tubular shape, the size of the porous support is not particularly limited, but is practically about 2 to 200 cm in length, 0.5 to 2 cm in inner diameter, and about 0.5 to 4 mm in thickness.
（３）種結晶の付着
種結晶を含むスラリーを多孔質支持体に付着させるには、多孔質支持体の形状に応じてディップコート法、スプレーコート法、塗布法、濾過法等の方法を適宜選択する。多孔質支持体とスラリーとの接触時間は０．５〜６０分間が好ましく、１〜１０分間がより好ましい。
種結晶を付着させた後、多孔質支持体を乾燥させるのが好ましい。高温で乾燥させると、溶媒の蒸発が早く、種結晶粒子の凝集が多くなるため、均一な種結晶付着状態を壊してしまうおそれがあるので好ましくない。このため乾燥は７０℃以下で行うのが好ましい。加熱時間を短くするため、室温乾燥と加熱乾燥を組み合わせて行うのがより好ましい。乾燥は多孔質支持体が十分に乾燥するまで行えばよく、乾燥時間は特に限定されないが、通常２〜１２時間程度で良い。(3) Adhesion of seed crystal In order to adhere the slurry containing the seed crystal to the porous support, a method such as a dip coating method, a spray coating method, a coating method, or a filtration method is appropriately used according to the shape of the porous support. select. The contact time between the porous support and the slurry is preferably 0.5 to 60 minutes, more preferably 1 to 10 minutes.
It is preferable to dry the porous support after depositing the seed crystals. Drying at a high temperature is not preferable because the solvent evaporates quickly and the seed crystal particles agglomerate, which may destroy the uniform seed crystal adhesion state. For this reason, it is preferable to perform drying at 70 degrees C or less. In order to shorten the heating time, it is more preferable to combine room temperature drying and heat drying. Drying may be performed until the porous support is sufficiently dried, and the drying time is not particularly limited, but is usually about 2 to 12 hours.
［２］ゼオライトの合成反応
多孔質支持体上でのゼオライト膜の合成は、水熱合成法、気相法等により行うことができる。以下水熱合成法を例にとって、ゼオライト膜の合成方法を説明するが、本発明はこれに限定されない。[2] Synthesis Reaction of Zeolite The synthesis of the zeolite membrane on the porous support can be performed by a hydrothermal synthesis method, a gas phase method or the like. Hereinafter, a method for synthesizing a zeolite membrane will be described by taking a hydrothermal synthesis method as an example, but the present invention is not limited to this.
（１）原料
水熱反応の原料を水に加えて撹拌し、ゼオライト合成反応に使用する反応溶液又はスラリーを作製する。原料はアルミナ源及びシリカ源と、必要に応じてアルカリ金属源及び／又はアルカリ土類金属源である。アルミナ源としては、水酸化アルミニウム、アルミン酸ナトリウム、硫酸アルミニウム、硝酸アルミニウム、塩化アルミニウム等のアルミニウム塩の他、アルミナ粉末、コロイダルアルミナ等が挙げられる。シリカ源としては、ケイ酸ナトリウム、水ガラス、ケイ酸カリウム等のアルカリ金属ケイ酸塩の他、シリカ粉末、ケイ酸、コロイダルシリカ、ケイ素アルコキシド（アルミニウムイソプロポキシド等）等が挙げられる。アルカリ（土類）金属源としては、塩化ナトリウム、塩化カリウム、塩化カルシウム、塩化マグネシウム等が挙げられる。アルカリ金属ケイ酸塩は、シリカ源及びアルカリ金属源として兼用できる。(1) Raw material The raw material of the hydrothermal reaction is added to water and stirred to prepare a reaction solution or slurry used for the zeolite synthesis reaction. The raw materials are an alumina source and a silica source and, if necessary, an alkali metal source and / or an alkaline earth metal source. Examples of the alumina source include aluminum powder, aluminum aluminate, aluminum sulfate, aluminum nitrate, aluminum chloride, alumina powder, colloidal alumina, and the like. Examples of the silica source include alkali metal silicates such as sodium silicate, water glass and potassium silicate, silica powder, silicic acid, colloidal silica, silicon alkoxide (aluminum isopropoxide, etc.) and the like. Examples of the alkali (earth) metal source include sodium chloride, potassium chloride, calcium chloride, magnesium chloride and the like. The alkali metal silicate can be used as both a silica source and an alkali metal source.
シリカ源とアルミナ源のモル比（ＳｉＯ２／Ａｌ２Ｏ３に換算）は、目的とするゼオライトの組成によって適宜決定するが、一般には１以上であり、好ましくは２以上である。
反応溶液又はスラリー中のシリカ源＋アルミナ源の含有量は特に限定されないが、５０〜９９．５質量％であるのが好ましく、６０〜９０質量％であるのがより好ましい。シリカ源＋アルミナ源の含有量が５０質量％未満であるとゼオライトの合成反応が遅すぎ、また９９．５質量％超であると均一なゼオライト膜が形成し難い。
反応溶液又はスラリーに、ゼオライトの結晶化促進剤を添加しても良い。結晶化促進剤としては、テトラプロピルアンモニウムブロマイドや、テトラブチルアンモニウムブロマイド等が挙げられる。The molar ratio of silica source to alumina source (converted to SiO2 / Al2O3) is appropriately determined depending on the composition of the target zeolite, but is generally 1 or more, preferably 2 or more.
The content of the silica source + alumina source in the reaction solution or slurry is not particularly limited, but is preferably 50 to 99.5% by mass, and more preferably 60 to 90% by mass. If the content of silica source + alumina source is less than 50% by mass, the synthesis reaction of zeolite is too slow, and if it exceeds 99.5% by mass, a uniform zeolite film is difficult to form.
A zeolite crystallization accelerator may be added to the reaction solution or slurry. Examples of the crystallization accelerator include tetrapropylammonium bromide and tetrabutylammonium bromide.
（２）加熱処理
種結晶を付着させた多孔質支持体に反応溶液又はスラリーを接触させ（例えば反応溶液又はスラリー中に浸漬し）、加熱処理する。加熱温度は４０〜２００℃が好ましく、８０〜１５０℃がより好ましい。加熱温度が４０℃未満であると、ゼオライトの合成反応が十分に起こらない。また２００℃超であると、ゼオライトの合成反応を制御するのが困難であり、均一なゼオライト膜が得られない。加熱時間は加熱温度に応じて適宜変更し得るが、一般に１〜１００時間であれば良い。なお水系の反応溶液又はスラリーを１００℃超の温度に保持する場合、オートクレーブ中で加熱すれば良い。(2) Heat treatment The reaction solution or slurry is brought into contact with the porous support to which the seed crystal is attached (for example, immersed in the reaction solution or slurry), and heat treatment is performed. The heating temperature is preferably 40 to 200 ° C, more preferably 80 to 150 ° C. When the heating temperature is less than 40 ° C., the zeolite synthesis reaction does not occur sufficiently. If it exceeds 200 ° C., it is difficult to control the synthesis reaction of zeolite, and a uniform zeolite membrane cannot be obtained. The heating time can be appropriately changed according to the heating temperature, but generally it may be 1 to 100 hours. In addition, what is necessary is just to heat in an autoclave, when hold | maintaining an aqueous reaction solution or slurry at the temperature over 100 degreeC.
［３］ゼオライト膜
本発明の製造方法により、ＭＦＩ型、Ａ型、Ｔ型等、種々の組成及び構造を有するゼオライト膜を製造できる。これらのゼオライト膜は分離膜として使用できる。
得られるゼオライト膜を分離膜として使用する場合、その性能は分離係数により表すことができる。例えばエタノールと水を分離する場合、分離前の水の濃度をＡ１質量％、エタノールの濃度をＡ２質量％とし、膜を透過した液体又は気体中の水の濃度をＢ１質量％、エタノールの濃度をＢ２質量％とすると、下記式（２）：
α＝（Ｂ１／Ｂ２）／（Ａ１／Ａ２）・・・（２）
により表されるものである。分離係数αが大きいほど、分離膜の性能が良いことになる。[3] Zeolite membrane Zeolite membranes having various compositions and structures such as MFI type, A type, and T type can be produced by the production method of the present invention. These zeolite membranes can be used as separation membranes.
When the obtained zeolite membrane is used as a separation membrane, its performance can be expressed by a separation factor. For example, when separating ethanol and water, the concentration of water before separation is A1% by mass, the concentration of ethanol is A2% by mass, the concentration of water in the liquid or gas that has passed through the membrane is B1% by mass, and the concentration of ethanol is Assuming that B2% by mass, the following formula (2):
α = (B1 / B2) / (A1 / A2) (2)
It is represented by. The larger the separation coefficient α, the better the performance of the separation membrane.
鋭意研究の結果、ゼオライト膜の分離係数αはゼオライト種結晶を含むスラリー中のゼオライト種結晶の濃度と相関することが分かった。すなわち、分離係数αとゼオライト種結晶の濃度との間には、下記式（１）：
α＝Ｍ０・ｅｘｐ（Ｍ１・Ｘ）・・・（１）
（ただし、Ｘはゼオライト種結晶を含むスラリー中のゼオライト種結晶の濃度（質量％）を示し、Ｍ０及びＭ１は３１５≦Ｍ０≦１．４×１０５、−４．１６≦Ｍ１≦−０．８を満たす定数である。）の関係が成立することが分かった。Ｍ０及びＭ１はゼオライトの種類により決まる定数である。As a result of intensive studies, it has been found that the separation factor α of the zeolite membrane correlates with the concentration of the zeolite seed crystals in the slurry containing the zeolite seed crystals. That is, between the separation factor α and the concentration of the zeolite seed crystal, the following formula (1):
α = M0 · exp (M1 · X) (1)
(X represents the concentration (mass%) of the zeolite seed crystal in the slurry containing the zeolite seed crystal, and M0 and M1 are 315 ≦ M0 ≦ 1.4 × 105, −4.16 ≦ M1 ≦ −0.8. It is clear that the relationship is satisfied. M0 and M1 are constants determined by the type of zeolite.
このように分離係数αはゼオライト種結晶を含むスラリー中のゼオライト種結晶の濃度Ｘに依存するため、スラリー中のゼオライトの濃度Ｘを制御することにより、所望の分離係数を有するゼオライト膜を製造することが可能となる。例えばエタノールと水の分離膜では、１０００以上の分離係数αが好ましいが、このような分離係数αを有するゼオライト膜を製造するためのゼオライト種結晶を含むスラリー中のゼオライト種結晶の濃度Ｘは０．１〜１０％である。 Thus, since the separation factor α depends on the concentration X of the zeolite seed crystals in the slurry containing the zeolite seed crystals, the zeolite membrane having a desired separation coefficient is manufactured by controlling the concentration X of the zeolite in the slurry. It becomes possible. For example, in the separation membrane of ethanol and water, a separation factor α of 1000 or more is preferable, but the concentration X of the zeolite seed crystal in the slurry containing the zeolite seed crystal for producing a zeolite membrane having such a separation factor α is 0. .1-10%.
［本発明のポイント］
本発明は、支持体の細孔内に形成されるゼオライト層を制御して、ゼオライト膜全体における透過成分の透過量を向上させるものである。
ゼオライト膜は、一般的に、セラミクスなどの多孔質の支持体上に形成される。ゼオライト膜の分離膜としての特性は、膜を透過する成分の透過量と分離処理の前後における透過する成分の濃度の比率（分離選択性）によって評価される。
ゼオライト膜の開発においては、分離選択性の向上が図られる。本発明のような多孔質支持体へのゼオライト膜の形成において、その分離選択性を決める要因として、ゼオライト膜全体の緻密性を向上させる必要がある。膜の緻密性が低く、例えばピンホールなどがゼオライト膜に存在すると、そのピンホールを介して、透過成分と共に非透過成分もゼオライト膜を透過することとなり、その分離選択性は低下してしまう。よって、本発明の分離膜においても、その分離選択性が十分に高いことが大前提としてある。[Points of the present invention]
The present invention controls the zeolite layer formed in the pores of the support to improve the permeation amount of the permeation component in the entire zeolite membrane.
The zeolite membrane is generally formed on a porous support such as ceramics. The characteristics of the zeolite membrane as a separation membrane are evaluated by the ratio of the permeation amount of the component that permeates the membrane and the concentration of the permeated component before and after the separation treatment (separation selectivity).
In the development of a zeolite membrane, the separation selectivity can be improved. In the formation of a zeolite membrane on a porous support as in the present invention, it is necessary to improve the density of the entire zeolite membrane as a factor for determining the separation selectivity. If the membrane is low in density, for example, if pinholes or the like are present in the zeolite membrane, the permeation component and the non-permeation component also permeate through the zeolite membrane through the pinhole, and the separation selectivity is lowered. Therefore, the separation membrane of the present invention is also premised on its sufficiently high separation selectivity.
これに対して、透過量を決定する要因としては、透過成分がゼオライト膜全体を透過する際に、どれだけの抵抗を受けるか否かによって決定されると考えられる。すなわち、ゼオライト自身の物性および支持体の物性が固定されたものであると考えれば、この透過量は、ゼオライト膜の膜厚によって決定されるものである。一般的には、支持体の外部に形成されるゼオライト膜の膜厚を薄くすることが第一に考えられ、発明者らも、上述した分離選択性が損なわれない程度まで、支持体の外部に形成されるゼオライト膜の膜厚を薄くし、その透過量の向上に成功した。 On the other hand, it is considered that the factor that determines the permeation amount is determined by how much resistance the permeation component receives when it permeates the entire zeolite membrane. That is, if it is considered that the physical properties of the zeolite itself and the physical properties of the support are fixed, the permeation amount is determined by the thickness of the zeolite membrane. In general, it is first considered to reduce the thickness of the zeolite membrane formed on the outside of the support, and the inventors have made the outside of the support to the extent that the above-described separation selectivity is not impaired. The thickness of the zeolite membrane formed on the surface was reduced and the permeation amount was successfully improved.
さらに、作製したゼオライト膜を詳しく観察したところ、支持体の細孔内部にも緻密にゼオライト膜が形成されていることがわかった。基本的にゼオライト膜の分離選択性は、支持体の外部に形成されるゼオライト膜の緻密性によって担保されるものであると考えられる。また、そのように支持体の細孔内部に形成されたゼオライト結晶は、前述したような透過成分が透過する際の抵抗となり、透過量低下の原因となりうる。 Furthermore, when the produced zeolite membrane was observed in detail, it was found that a dense zeolite membrane was also formed inside the pores of the support. Basically, it is considered that the separation selectivity of the zeolite membrane is ensured by the denseness of the zeolite membrane formed outside the support. In addition, the zeolite crystal formed in the pores of the support as described above becomes a resistance when the permeation component permeates as described above, and may cause a decrease in the permeation amount.
そこで、発明者らは、支持体の細孔内部にゼオライト結晶が緻密に形成されていないような構造を実現できればさらなる透過量の向上が見込めると考え、鋭意研究の結果、当該構造の実現に至った。 Therefore, the inventors believe that further improvement in the amount of permeation can be expected if a structure in which the zeolite crystals are not densely formed inside the pores of the support can be realized, and as a result of earnest research, the structure has been realized. It was.
本発明を以下の実施例によってさらに詳細に説明するが、本発明はそれらに限定されるものではない。
（実施例）
Ａ型ゼオライトの微粒子の粉体を水に入れて撹拌し、０．５質量％の濃度に調整したスラリーを３つ作製した。３つのスラリーの微粒子の平均粒径は、それぞれ１００ｎｍ、３００ｎｍおよび５００ｎｍとした。そして、α−アルミナからなる管状多孔質支持体（平均細孔径１．３μｍ、外径１０ｍｍ、内径６ｍｍ、長さ１３ｃｍ）を３つ用意し、この３つの管状多孔質支持体を各スラリーにそれぞれ３分間浸漬した後、約０．２ｃｍ／ｓの速度で引き上げた。これを２５℃の恒温槽中で２時間乾燥した後、７０℃の恒温槽中で１６時間乾燥した。乾燥後の各多孔質支持体を走査型電子顕微鏡で観察した結果、それぞれの多孔質支持体表面に種結晶が均質に付着していることが確認された。The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
(Example)
Three fine particles of A-type zeolite fine particles were put in water and stirred to prepare three slurries adjusted to a concentration of 0.5% by mass. The average particle sizes of the fine particles of the three slurries were 100 nm, 300 nm, and 500 nm, respectively. And three tubular porous supports (average pore diameter 1.3 μm,
ケイ酸ナトリウム、水酸化アルミニウム及び蒸留水を、各成分のモル比がＳｉＯ２／Ａｌ２Ｏ３＝２、Ｎａ２Ｏ／ＳｉＯ２＝１、Ｈ２Ｏ／Ｎａ２Ｏ＝７５となるように混合し、水熱反応溶液とした。この反応溶液に種結晶層を付与した多孔質支持体を浸漬して、１００℃で４時間保持した結果、多孔質支持体の表面にゼオライト膜が形成された。ゼオライト膜のＸ線回折パターンを図１に示し、ゼオライト膜の表面の走査型電子顕微鏡写真を図２に示す。図１、図２から、緻密な表面を有するＡ型ゼオライトの結晶層が形成されていることがわかった。 Sodium silicate, aluminum hydroxide, and distilled water were mixed so that the molar ratio of each component was SiO2 / Al2O3 = 2, Na2O / SiO2 = 1, and H2O / Na2O = 75 to obtain a hydrothermal reaction solution. As a result of immersing the porous support provided with the seed crystal layer in this reaction solution and keeping it at 100 ° C. for 4 hours, a zeolite membrane was formed on the surface of the porous support. An X-ray diffraction pattern of the zeolite membrane is shown in FIG. 1, and a scanning electron micrograph of the surface of the zeolite membrane is shown in FIG. 1 and 2, it was found that a crystal layer of A-type zeolite having a dense surface was formed.
ここで、以下の説明において、管状多孔質支持体に平均粒径が１００ｎｍの微粒子が付着され、ゼオライト膜が形成されることによって得られた分離膜のことを第１の分離膜、管状多孔質支持体に平均粒径が３００ｎｍの微粒子が付着され、ゼオライト膜が形成されることによって得られた分離膜のことを第２の分離膜、管状多孔質支持体に平均粒径が５００ｎｍの微粒子が付着され、ゼオライト膜が形成されることによって得られた分離膜のことを第３の分離膜という。 Here, in the following description, the separation membrane obtained by attaching fine particles having an average particle diameter of 100 nm to the tubular porous support and forming a zeolite membrane is referred to as the first separation membrane, tubular porous The separation membrane obtained by attaching fine particles having an average particle size of 300 nm to the support and forming a zeolite membrane is the second separation membrane, and the fine particles having an average particle size of 500 nm are formed on the tubular porous support. A separation membrane obtained by adhering and forming a zeolite membrane is referred to as a third separation membrane.
得られた分離膜の分離性能を評価するために、図３に示すパーベーパレーション（ＰＶ）試験装置を組み立てた。このＰＶ試験装置は、供給液Ａの供給を受ける管１１及び攪拌装着１２を具備する容器１と、容器１の内部に設置された分離器２と、分離器２の開放端に連結した管６と、管６の末端に液体窒素トラップ３を介して接続した真空ポンプ４とを有する。分離器２は、上記のように多孔質支持体の表面にゼオライト膜が形成したものである。なお管６の途中には真空ゲージ５が取り付けられている。 In order to evaluate the separation performance of the obtained separation membrane, a pervaporation (PV) test apparatus shown in FIG. 3 was assembled. This PV test apparatus includes a
このＰＶ試験装置の容器１に、管１１を介して７５℃の供給液Ａ（エタノール／水の質量比＝９０／１０）を供給し、真空ポンプ４により分離器２内を吸引した（真空ゲージ５による真空度：１０〜１０００Ｐａ）。分離器２を透過した液Ｂは液体窒素トラップ３で捕集された。供給液Ａと透過液Ｂの組成をガスクロマトグラフ［（株）島津製作所製 ＧＣ−１４Ｂ］を用いて測定し、各分離膜の透過係数と分離係数を求めた。測定結果を表１に示す。
表１に示すように、双方の分離膜において、それらの分離係数は１００００以上であり、ピンホールの無い良質なゼオライト膜が管状多孔質支持体の全面に渡って形成されていることを示していた。これに対して、各分離膜の透過係数については、第１の分離膜では２．９［ｋｇ／ｍ２・ｈ］、第２の分離膜では４．１［ｋｇ／ｍ２・ｈ］、第３の分離膜では５．１［ｋｇ／ｍ２・ｈ］と大きな違いが見られた。 As shown in Table 1, in both separation membranes, the separation factor is 10,000 or more, indicating that a high-quality zeolite membrane without a pinhole is formed over the entire surface of the tubular porous support. It was. On the other hand, the permeability coefficient of each separation membrane is 2.9 [kg /
各分離膜の断面をＳＥＭ（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｙ、走査型電子顕微鏡）観察した。その像を、図４（第１の分離膜）、図５（第２の分離膜）、図６（第３の分離膜）に示す。
第１の分離膜において、図４に示すように、表面付近には連続的および緻密に形成されたゼオライト結晶よりなるゼオライト膜が形成され、細孔内には、表面からの深さ３０μｍ以上の部分にまで、ゼオライト結晶が緻密に形成されている。The cross section of each separation membrane was observed by SEM (Scanning Electron Microscopy, scanning electron microscope). The images are shown in FIG. 4 (first separation membrane), FIG. 5 (second separation membrane), and FIG. 6 (third separation membrane).
In the first separation membrane, as shown in FIG. 4, a zeolite membrane made of zeolite crystals formed continuously and densely is formed in the vicinity of the surface, and a depth of 30 μm or more from the surface is formed in the pores. Zeolite crystals are densely formed up to the part.
また、第２の分離膜においても、図５に示すように、第１の分離膜と同様に表面付近には連続的および緻密に形成されたゼオライト結晶よりなるゼオライト膜が形成され、細孔内にも、表面からの深さ３０μｍ以上の部分にまで、ゼオライト結晶が形成されている。ただし、図４と図５とを比較すると、細孔内に形成されたゼオライト結晶の総量に違いが見られる。 Also in the second separation membrane, as shown in FIG. 5, a zeolite membrane composed of continuous and densely formed zeolite crystals is formed in the vicinity of the surface as in the first separation membrane, In addition, zeolite crystals are formed up to a depth of 30 μm or more from the surface. However, when FIG. 4 and FIG. 5 are compared, there is a difference in the total amount of zeolite crystals formed in the pores.
これに対して、第３の分離膜においては、図６に示すように、表面付近には上記２つの分離膜と同様のゼオライト膜が形成されているが、細孔内には、他の二つの分離膜と異なり、表面からの深さ１０μｍ以下の部分には、ゼオライト結晶が殆ど形成されていない。 On the other hand, in the third separation membrane, as shown in FIG. 6, a zeolite membrane similar to the two separation membranes is formed in the vicinity of the surface. Unlike two separation membranes, almost no zeolite crystals are formed in a portion having a depth of 10 μm or less from the surface.
細孔内に形成されたゼオライト結晶の量を定量的に確認するために、各分離膜の断面をＥＤＸ分析（Ｅｎｅｒｇｙ Ｄｉｓｐｅｒｓｉｖｅ Ｘ−ｒａｙ Ｆｌｕｏｒｅｓｃｅｎｃｅ Ｓｐｅｃｔｒｏｓｃｏｐｙ、エネルギー分散型蛍光Ｘ線分析）の面分析を施し、深さ方向におけるゼオライト結晶の量の相対変化を調べた。詳しくは、各分離膜はアルミナ支持体上にゼオライト結晶が形成されたものであるので、ゼオライト結晶に含まれるＳｉの検出量の相対変化を調べることで、深さ方向におけるゼオライト結晶の量の相対変化を調べた。ここでは、深さ２μｍごとの面分析を行った。その結果を、図７に示す。 In order to quantitatively confirm the amount of zeolite crystals formed in the pores, the cross section of each separation membrane was subjected to surface analysis of EDX analysis (Energy Dispersive X-ray Fluorescence Spectroscopy, energy dispersive X-ray fluorescence analysis). The relative change in the amount of zeolite crystals in the depth direction was investigated. Specifically, since each separation membrane has a zeolite crystal formed on an alumina support, the relative change in the amount of zeolite crystal in the depth direction can be determined by examining the relative change in the amount of Si detected in the zeolite crystal. We examined changes. Here, a surface analysis was performed every 2 μm in depth. The result is shown in FIG.
図７からも、ＳＥＭ観察で得られた結果と同様に、第３の分離膜では、分離膜の表面１０μｍの深さよりも深いところでは支持体の細孔内にゼオライト結晶が殆ど形成されていないことがわかる。また、第１の分離膜および第２の分離膜についても、ＳＥＭ観察より得られた結果と同様のデータが得られた。
ここで、さらに、深さ４μｍごとの面分析および深さ１０μｍごとの面分析を行った。その結果を図８および図９にそれぞれ示す。図８および図９からもさらにわかるように、第３の分離膜では、第１および第２の分離膜と比べて、形成されているゼオライト結晶の総量が少ないことがわかる。これを数値化すると、分離膜の表面から深さ１０μｍまでのゼオライト結晶の総量Ｍ１と、分離膜の表面からの深さ１０μｍから表面からの深さ２０μｍまでのゼオライト結晶の総量Ｍ２との関係をＭ２／Ｍ１で表すと、第１、第２および第３の分離膜において、それぞれ０．５８、０．３６および０．１１であった。さらに、分離膜の表面から深さ４μｍまでのゼオライト結晶の総量Ｍ３と、分離膜の表面からの深さ１２μｍから表面からの深さ１６μｍまでのゼオライト結晶の総量Ｍ４との関係をＭ４／Ｍ３で表すと、第１、第２および第３の分離膜において、それぞれ０．５２、０．２１および０．０５であった。From FIG. 7 as well, similar to the result obtained by SEM observation, in the third separation membrane, almost no zeolite crystals are formed in the pores of the support at a depth deeper than the surface of the separation membrane of 10 μm. I understand that. Moreover, the same data as the result obtained by SEM observation was obtained also about the 1st separation membrane and the 2nd separation membrane.
Here, a surface analysis every depth of 4 μm and a surface analysis every depth of 10 μm were performed. The results are shown in FIGS. 8 and 9, respectively. As can be further understood from FIGS. 8 and 9, it can be seen that the total amount of zeolite crystals formed in the third separation membrane is smaller than that in the first and second separation membranes. When this is quantified, the relationship between the total amount M1 of zeolite crystals from the surface of the separation membrane to a depth of 10 μm and the total amount of zeolite crystals M2 from the depth of 10 μm from the surface of the separation membrane to a depth of 20 μm from the surface. In terms of M2 / M1, the values were 0.58, 0.36, and 0.11, respectively, in the first, second, and third separation membranes. Furthermore, the relationship between the total amount M3 of zeolite crystals from the surface of the separation membrane to a depth of 4 μm and the total amount of zeolite crystals M4 from the depth of 12 μm from the surface of the separation membrane to a depth of 16 μm from the surface is M4 / M3. As a result, in the first, second and third separation membranes, they were 0.52, 0.21 and 0.05, respectively.
ゼオライト膜の形成という観点から考察すると次のように考えられる。すなわち、第１の分離膜においては、ゼオライト膜の合成が行なわれる前に支持体に付着していた微粒子の平均粒径が１００ｎｍと比較的小さいために、種結晶の担持工程において、支持体の表面から３０μｍ程度の深い場所にまで種結晶が浸透し、支持体内部に付着してしまう。この結果、ゼオライト膜の形成時に支持体内部深いところでも、種結晶を核として多量のゼオライト結晶が形成された。さらには、支持体に担持されている種結晶のサイズが小さいため、ゼオライト結晶の形成時に用いる反応液が支持体の奥深く浸透し易く、流れ込む反応溶液の量が多くなるため、支持体内部に形成されるゼオライト結晶の総量が比較的多くなってしまう。 Considering from the viewpoint of forming a zeolite membrane, it is considered as follows. That is, in the first separation membrane, the average particle size of the fine particles adhering to the support before the synthesis of the zeolite membrane is relatively small as 100 nm. The seed crystal penetrates to a depth of about 30 μm from the surface and adheres to the inside of the support. As a result, a large amount of zeolite crystals were formed with the seed crystals as nuclei even deep inside the support during the formation of the zeolite membrane. Furthermore, since the size of the seed crystal supported on the support is small, the reaction solution used when forming the zeolite crystals easily penetrates deep into the support, and the amount of the reaction solution that flows in increases, so it forms inside the support. The total amount of zeolite crystals produced is relatively large.
これに対して、第３の分離膜においては、ゼオライト膜の合成が行なわれる前に支持体に付着していた微粒子の平均粒径が５００ｎｍと比較的大きいため、種結晶の担持工程において、支持体の表面から１０μｍ以上の深い場所にまで種結晶が殆ど浸透せず、支持体内部での付着量も少ない。この結果、ゼオライト膜の形成時に支持体内部１０μｍ以上では種結晶が殆ど存在しないため、種結晶を核としたゼオライト結晶がないものと考えられる。さらには、支持体に担持されている種結晶のサイズが大きいため、ゼオライト結晶の形成時に用いる反応液が支持体の奥深くまで浸透せず、流れ込む反応溶液の量も少ないため、支持体内部に形成されるゼオライト結晶の総量も比較的少なくなると考えられる。 On the other hand, in the third separation membrane, the average particle size of the fine particles adhering to the support before the synthesis of the zeolite membrane is relatively large as 500 nm. The seed crystal hardly penetrates from the surface of the body to a deep place of 10 μm or more, and the amount of adhesion inside the support is small. As a result, it is considered that there is no zeolite crystal with the seed crystal as a nucleus because almost no seed crystal exists at the inside of the support of 10 μm or more when forming the zeolite membrane. Furthermore, because the size of the seed crystal supported on the support is large, the reaction solution used when forming zeolite crystals does not penetrate deep into the support, and the amount of reaction solution that flows in is small, so it forms inside the support. It is believed that the total amount of zeolite crystals produced is also relatively small.
このように、支持体に付着させる種結晶のサイズを大きくすることにより、支持体内部に形成されるゼオライト結晶の総量を減少させることができる。
また、第３の分離膜のように支持体内部に形成されるゼオライト結晶の総量を減少させることにより、透過成分が分離膜内を透過していく際の透過抵抗を減少させることができる。これにより、分離膜の性能指標の１つである透過係数を向上させることができるThus, the total amount of zeolite crystals formed inside the support can be reduced by increasing the size of the seed crystal attached to the support.
Further, by reducing the total amount of zeolite crystals formed inside the support like the third separation membrane, the permeation resistance when the permeation component permeates through the separation membrane can be reduced. Thereby, the permeability coefficient which is one of the performance indexes of the separation membrane can be improved.
Claims (8)
ゼオライトの種結晶を含むスラリーを、ディップコート法、スプレーコート法又は塗布法により付着させた後に乾燥させて、種結晶を担持させる種結晶担持工程と、
種結晶が担持された前記多孔質支持体を所定の組成で予め用意されたゼオライト合成用反応液内に浸漬させ、水熱反応により多孔質支持体の表面および細孔内にゼオライト結晶を形成する結晶形成工程と
を備える分離膜の作製方法であって、
前記多孔質支持体の表面の平均細孔径が０．４μｍ〜１．５μｍであり、
前記スラリー中に含まれる種結晶の濃度が０．１〜２０質量％であり、
前記種結晶の平均径が０．３μｍ〜０．８μｍであり、
前記多孔質支持体の表面の平均細孔径をＲ、前記種結晶の平均径をＳとしたときに、Ｒ−Ｓ≦１．１μｍであり、かつ
前記多孔質支持体と前記スラリーとの接触時間が０．５〜６０分間、乾燥温度が７０℃以下である
ことを特徴とする分離膜の作製方法。 In a porous support having a predetermined average pore diameter ,
A seed crystal supporting step of supporting the seed crystal by drying the slurry containing the zeolite seed crystal by a dip coating method, a spray coating method or a coating method;
The porous support carrying a seed crystal is immersed in a zeolite synthesis reaction solution prepared in advance with a predetermined composition, and a zeolite crystal is formed on the surface and pores of the porous support by a hydrothermal reaction. Crystal formation process and
A method for producing a separation membrane comprising:
The average pore diameter of the surface of the porous support is 0.4 μm to 1.5 μm,
The concentration of the seed crystals contained in the slurry is 0.1 to 20% by mass,
The average diameter of the seed crystal is 0.3 μm to 0.8 μm,
R−S ≦ 1.1 μm, where R is the average pore diameter of the surface of the porous support and S is the average diameter of the seed crystal, and
The contact time between the porous support and the slurry is 0.5 to 60 minutes, and the drying temperature is 70 ° C. or lower.
A method for producing a separation membrane.
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| JP2005262189A (en) | 2005-09-29 |
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